Even if they have, they are known for super strict security rules, so it won't be disclosed. I saw a link to their patent application where they patented a way to protect the current keyboard design from dust and crumbs. Personally, I got tired of their disregard for software developers issues with hardware, and now my working machine in the new XPS 13 from Dell. I am happy with it.
As an EE, I despise using laptops, rather want real engineering workstations. So what is it with software developers and laptops? The portability? Or rather people just being used to a laptop since they are ubiquitous in college. Even plugged into monitors, laptop keyboards just plain suck. I have an XPS-13, and it's handy for field use with GNU Radio, but can't fathom doing anything productive on it.
As a different way of looking at it, as an Electronic Engineer (I hope I got the right acronym), some of the software you run may well require a bit more performance than most software engineers need.
I think a mobile i7, 16GB of fast RAM, and a fast SSD is pretty good for most developers now, particularly when we're not compiling code - we're mostly using scripting languages (at least the type of devs around here) so the development cycle depends more on reloading and parsing files off disk than on intensive compilation and optimisation steps. There are definitely software engineers who need more, but many will do just fine on a laptop, and the portability wins out.
Compared to Electronic Engineering, I remember some of the software that EE students used at the uni I went to required some beefy hardware to run on. It was large complicated software, that I'd put in the same category as 3D modelling suites, or video editing/effects/rendering. It required high performance workstations, and higher performance simulation servers. I can totally see why an Electronic Engineer would prefer a workstation (although I think to call it a "real" workstation would be a little disingenuous, it depends what your engineering is!)